id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
3030	unique=True and db_index=True leads to duplicated indexes	fte@…	nobody	"At least in MySQL this produces a doubled index.

Example:

{{{
class Kunde(models.Model):
    kundenid  = models.AutoField(primary_key=True)
    loginname = models.CharField(unique=True, maxlength=50, db_index=True)
}}}


produces:

{{{
CREATE TABLE `mgt_kunden` (
    `kundenid`integer AUTO_INCREMENT NOT NULL PRIMARY_KEY,
    `loginname` varchar(50) NOT NULL UNIQUE
);
CREATE UNIQUE INDEX mgt_kunden_loginname ON `mgt_kunden` (`loginname`);
}}}

So there is the automatically generated index from the UNIQUE keyword
and the additional index requested by db_index=True.
"	enhancement	closed	Database layer (models, ORM)	dev	trivial	duplicate	db-be-api manage.py sqlall unique db_index	gabor@…	Accepted	1	0	1	0	0	0